1. Technical Field
The present application relates generally to electronic devices having a laser scan unit (LSU), and particularly to improved electrophotographic devices having reduced jitter and scan line variability for on-axis based LSU systems.
2. Description of the Related Art
In an LSU of an electrophotographic color imaging device, it is typical for each imaging channel to have its own optical sensor, called an “hsync sensor,” to detect its laser beam having been deflected from a polygonal mirror and to create a beam detect signal for use in triggering video data being included in the channel's laser beam for impinging on the channel's corresponding photoconductive drum. In more recent LSU design architectures, two beams share a single hsync sensor with one of the channels creating the start of scan (SOS) signal and the other channel using a delayed version of that SOS signal. Because one channel is imaging off of a facet of the rotating polygonal mirror that is not associated with the optical sensor generating the SOS signal, scan jitter can be induced into that channel. With such LSUs generating laser beams on-axis relative to the facets of the rotating polygonal mirror, the laser beams impinge on the polygon mirror such that only the variation in one or more facet cuts of the mirror is seen to induce scan jitter.
What is needed, then, is an improved LSU system which reduces or substantially eliminates scan jitter induced by facet cut variation of the polygonal mirror of an LSU.